Inverter-integrated electrical compressors in which an inverter device is integrally incorporated are used as air conditioner compressors installed in electric vehicles, hybrid vehicles, or the like. The inverter-integrated electrical compressor is configured to be driven by converting high-voltage DC power supplied from a power supply unit installed in the vehicle into three-phase AC power of a specified frequency, and applying the converted power to the electric motor.
An inverter device is configured from, e.g., high-voltage electric components, such as inductor coils, smoothing capacitors, and the like, which constitute a noise canceling filter circuit connecting with a high-voltage line, an inverter circuit, which includes a plurality of semiconductor switching elements, such as IGBT (Insulated Gate Bipolar Transistors), that convert direct current power to three-phase alternating current power, a control circuit, which includes a CPU (Central Processing Unit) or the like that controls the inverter circuit with instructions from a host control device, and a busbar or the like that interconnects these subassemblies and is constituted to convert high-voltage direct current power that is input via a P-N terminal into three-phase alternating current power, which is then output from a UWV terminal.
This inverter device is installed inside an inverter-accommodating case that is furnished in the electrical compressor housing, and is constituted to apply three-phase alternating current power from the UVW terminal to an electric motor via a sealed terminal that penetrates the housing. The inverter-accommodating case is established by means of a partitioning wall (housing wall) facing low-pressure refrigerant channels that pass through the interior of the housing, and is constituted so that the semiconductor switching elements and high-voltage electric components of the inverter device assembled in the interior thereof are cooled using this partitioning wall as a heat sink, and is hermetically sealed after the inverter device is assembled therein.
Expensive polyol ester (POE) refrigeration lubricant with high insulating performance is generally used in electrical compressors with a built-in electric motor. However, there are also users that prefer inexpensive polyalkyl glycol (PAG) refrigeration lubricant, which has low insulating performance. In this case, sufficient insulation must be ensured between the sealed terminal and the motor winding. In response to this, Patent Document 1 discloses that it is possible to ensure a sufficient insulating distance and to install an insulation member for the terminals inside the housing by raising the height of the partitioning wall inside the inverter-accommodating case, installing a sealed terminal in that portion.
Also, if cooling performance is ensured by disposing the semiconductor switching elements on the partitioning wall in the technology shown in Patent Document 1, the space for installing the circuit board on which the semiconductor switching elements are mounted is subject to restriction by the raised portion in which the sealed terminal is installed. Therefore, it becomes necessary to divide the circuit board into a power circuit board and a control substrate, requiring a busbar to interconnect the power circuit board and the sealed terminal. Meanwhile, if only one circuit board is used and semiconductor switching elements and high-voltage electric components are mounted thereon, as shown in Patent Document 2, the height of the partitioning wall must be raised to bring the part thereof on which the semiconductor switching elements are mounted closer to the circuit board.